Never mind the LD switchers, the biggest threat to Labour was already in the Red column

One assertion that receives a regular hearing on politicalbetting is that Labour is in an extremely strong position to win the next election thanks to that group of voters who switched from Lib Dem to Labour in 2010.Â Theyâ€™ve been consistent in their support ever since and remain favourably disposed towards Miliband and Labour.Â Add in that UKIPâ€™s support has come disproportionately from Con, that Labourâ€™s vote is more efficiently distributed, and that precious little direct Con-Lab has taken place (meaning itâ€™s unlikely much could swing back), and itâ€™s easy to see why many can picture Miliband on the steps of No 10 next May.

All of which is true but itâ€™s still not the whole picture.Â The weak spot in Labourâ€™s coalition is not those whoâ€™ve joined since 2010 â€“ those whoâ€™d traditionally be seen as swing voters â€“ itâ€™s those who were already there.

That may seem remarkable given that Labour polled their second-worst total since WWII in 2010, only just better than 1983.Â You would think that theyâ€™d have been somewhere near their base with a score like that.Â Yet history suggests itâ€™s entirely possible for a party to go backwards from a defeat: the Tories managed it in 2001 as did Labour in the aforementioned 1983.

And the risk is real enough: the August Mori poll reported Milibandâ€™s overall net satisfaction rating as -29%, in the same range as Hague and Duncan Smith when they were Leader of the Opposition.Â Even more concerning for him, some 41% of those saying theyâ€™d vote Labour were dissatisfied with him.Â Itâ€™s true that Cameronâ€™s net rating with Labour supporters is -52% but then youâ€™d expect supporters of one party to give poor scores to leaders of the others, especially when they rate their own so badly.Â Obviously, we shouldnâ€™t read too much into one or two subsamples from just one poll â€“ but this isnâ€™t just one poll: YouGovâ€™s results from 7-8 August, for example, had similar findings.

Even more notable is that Milibandâ€™s rating among 2010 Labour voters with Mori was -5%: itâ€™s only the LD switchers that pull his score into positive territory.Â YouGov recorded a small positive balance but still three in seven of Labourâ€™s 2010 support reported dissatisfaction.

Does this matter?Â Wonâ€™t those same core Labour voters, with their even lower opinion of Cameron, turn out even if unenthusiastically?Â Perhaps, but we shouldnâ€™t bank on it.Â It is, after all, easy to say youâ€™ll vote when responding over the phone or monitor.Â Going out and actually doing it in person (or even by post), is another thing: hence the disparity between how sure people say they are to vote and how many end up doing so (the Mori poll referred to earlier found 78% rating their likelihood to vote as between 7 and 10 out of 10).

Similarly, while theyâ€™re not likely to be tempted by the Tories or Lib Dems, Labourâ€™s coalition of voters includes groups who could find either UKIP or the Greens attractive.Â The Mori poll found a loss of 11% of Labourâ€™s 2010 vote to one or other of those two parties; the Tory figure for comparison was 13%.Â (YouGov found similar results; ICM, by contrast, reported a loss of just 4% of Labourâ€™s 2010 vote to Green or Purple, excluding Donâ€™t Knows).Â One could of course say that offers Labour an opportunity as well as a threat: if these voters could be persuaded to return, it places even less need on Team Miliband winning Tories over.Â Thatâ€™s true, but itâ€™s a big â€˜ifâ€™.